The present invention relates to the sterilization arts. It finds particular application in conjunction with steam sterilizers for medical, dental, and surgical equipment and will be discussed with particular reference thereto. It is to be appreciated, however, that the invention is also applicable to other high temperature sterilization and decontamination techniques.
Traditionally, steam sterilizers are used for destroying the microorganisms that may be present on medical equipment. Effective sterilization is achieved by a combination of temperature, pressure and exposure time. The sterilizer inner surface and the items to be sterilized are heated to the "saturation temperature" corresponding to the temperature at which water stays in the vapor form at a given pressure. If the saturation temperature is not maintained throughout the sterilization vessel, condensation may occur, resulting in the formation of water droplets. When living microorganisms become suspended in water, the water shields them from the steam. Moreover, as the water droplets run or are absorbed by sterile wraps or parts of the sterilized items, the water can carry the microorganisms through the sterile wraps and otherwise on to the previously sterilized items.
To prevent condensation, the walls of the pressure vessel in a conventional steam sterilizer are surrounded by a steam jacket. The steam jacket maintains the temperature of the vessel walls at or above the saturation temperature. This heats the items and structures in the pressure vessel, as well as the walls of the vessel above the saturation temperature.
Typically, the steam jacket consists of a metallic enclosure, around the pressure vessel. The steam is passed through a channel between the pressure vessel and the jacket walls. Heat from the steam is conducted through the walls of the pressure vessel, establishing and maintaining the temperature within the pressure vessel. Without such steam heating through the jacket, the metallic walls of the pressure vessel and the inner structures would be below the saturation temperature when steam is introduced to the pressure vessel.
Although the steam jacket is an effective way to heat the pressure vessel, such double walled pressure vessels are expensive to manufacture. Moreover, generating the steam to fill the jacket is expensive in energy, equipment, and time. The present invention provides a new and improved pressure vessel heating system which overcomes the above referenced problems and others.